Background
The number of patients with contact dermatitis from glucose sensors and insulin infusion sets is increasing. Patch testing is challenging because of a lack of information concerning the constituent materials of medical devices.

Objectives
To report on products and causes of allergic reactions to glucose sensors or insulin infusion sets over a 5-year period and suggest a short screening series.

Methods
Analysis of patch test data from consecutive patients suspected of allergic contact dermatitis (ACD) to glucose sensors and/or insulin infusion sets from 2015–2019.

Results
Patient numbers increased from 4 to 15 per year; 30/38 (78.9%) were children. In 29 (76.3%), a diagnosis of allergic/probable ACD was established, mostly due to the tapes of the device or allergens in these tapes (n = 23) followed by allergens in the device housing (n = 10). Isobornyl acrylate, abitol, and colophonium were the most common allergens. Information from manufacturers was often difficult to obtain and, if accessible, inadequate. For this reason, the diagnosis was delayed for more than 1.5 years in 12 (31%) patients.

Conclusions
The increasing number of patients, mostly children, with ACD from devices used in treatment of type 1 diabetes demonstrates the importance of this problem. Allergies can easily be overlooked, due to the lack of mandatory labeling of the constituent materials of the devices.